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Prevention of Endotracheal Suctioning-induced Alveolar Derecruitment in Acute Lung

Injury

Salvatore M. MAGGIORE1, Franois LELLOUCHE2, Jrme PIGEOT2, Solenne TAILLE2,

Nicolas DEYE2, Xavier DURRMEYER2, Jean-Christophe RICHARD3, Jordi MANCEBO4,

Franois LEMAIRE2, Laurent BROCHARD2

1 Department of Anesthesiology and Intensive Care, Agostino Gemelli Teaching Hospital,

Universit Cattolica del Sacro Cuore, Rome, Italy; 2Medical Intensive Care Unit, INSERM

U492, Henri Mondor Teaching Hospital, AP-HP, Paris XII University, Crteil, France; 3

Medical Intensive Care Unit, Charles Nicolle Teaching Hospital, Rouen, France; 4Servei de

Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain

Send all correspondence including reprint requests to:

Prof. L. Brochard, Ranimation Mdicale, Hpital Henri Mondor, 94000 Crteil, France.

Phone: +33 1 49 81 23 92; Fax: +33 1 42 07 99 43;

E-mail: [email protected]

This study was supported by INSERM U492. The equipment was kindly furnished by TYCO

Healthcare, CA, USA.

Running Title: Endotracheal Suctioning in Acute Lung Injury

Descriptor numbers:2 - 10 -13

Word count (text without abstract and references):4128

This article has an online data supplement, which is accessible from this issues table of

content online at www.atsjournals.org

Copyright (C) 2003 by the American Thoracic Society.

AJRCCM Articles in Press. Published on February 13, 2003 as doi:10.1164/rccm.200203-195OC
mailto:[email protected]://www.atsjournals.org/http://www.atsjournals.org/http://www.atsjournals.org/mailto:[email protected]

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ABSTRACT

We studied endotracheal suctioning-induced alveolar derecruitment and its prevention

in nine patients with acute lung injury. Changes in end-expiratory lung volume measured by

inductive plethysmography, PEEP-induced alveolar recruitment assessed by pressure-volume

curves, oxygen saturation, and respiratory mechanics were recorded. Suctioning was

performed after disconnection from the ventilator, through the swivel adapter of catheter

mount, with a closed system, and with the two latter techniques while performing recruitment

maneuvers during suctioning (40 cmH2O pressure-supported breaths). End-expiratory lung

volume after disconnection fell more than with all other techniques (-1466586, -733406, -

531228, -168176 and -284317 ml after disconnection, through the swivel adapter, with

the closed system, and with the two latter techniques with pressure-supported breaths,

respectively, p

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INTRODUCTION

It has been suggested that ventilator associated lung injury can be caused by high

transpulmonary pressures at the end of inspiration and/or insufficient recruitment at the end of

expiration, in patients with acute lung injury (ALI) and acute respiratory distress syndrome

(ARDS) (1). Preventing alveolar overdistension and derecruitment are the goals of recently

proposed protective ventilatory strategies. In this context, the periodic derecruitment induced

by endotracheal suctioning could be harmful in ALI/ARDS patients. In addition, the

application of a subatmospheric pressure generates alveolar injury in case of surfactant

dysfunction (2). Most of the studies on endotracheal suctioning have concentrated on

reversing or preventing hypoxemia resulting from such a procedure. Few data exist about the

effect of endotracheal suctioning on lung volumes (3-5), and no study has assessed the

consequences of suctioning on alveolar recruitment in ALI/ARDS. In patients with various

etiologies of acute respiratory failure, Brochard et al. demonstrated that one major mechanism

causing hypoxemia during suctioning was the decrease in lung volume induced by the loss of

positive alveolar pressure. This phenomenon could be prevented by the use of continuous

oxygen insufflation via a special endotracheal tube generating a positive pressure during

suctioning (3). The need to use a modified endotracheal tube, however, limits the clinical

application of this technique. Recently, Cereda et al. reported that using a closed suctioning

system allowed to prevent partially the fall of end-expiratory lung volume and hypoxemia

observed when endotracheal suctioning was performed after disconnection from the

ventilator, in patients with ALI (4). The effect of the closed system on the recruitment induced

by positive end-expiratory pressure (PEEP) was not studied. Lately, Lu et al. have shown that

a recruitment maneuver performed after endotracheal suctioning could reverse atelectasis

resulting from such a procedure, in an animal model (5). However, the prevention of the

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endotracheal suctioning-related lung volume loss could be more clinically relevant (6, 7). In

addition, whether a better prevention could be obtained by the use of special maneuvers

during suctioning needed to be studied.

The aims of our study were: 1) to assess the magnitude of lung volume fall during

endotracheal suctioning and determine the respective roles of PEEP loss and negative

pressure, 2) to assess the impact of endotracheal suctioning performed with different

techniques on alveolar recruitment/derecruitment in patients with ALI/ARDS, and 3) to try to

prevent derecruitment by performing a special recruitment maneuver during endotracheal

suctioning. We hypothesized that such a maneuver could prevent the alveolar derecruitment

and the decrease in oxygenation. The effect of different suctioning techniques on lung

volumes, alveolar recruitment/derecruitment, arterial oxygenation and respiratory mechanics

was assessed and compared in nine patients with ALI/ARDS.

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METHODS(word count = 499)

Patients

The institutional ethics committee approved the protocol. Written informed consent

was obtained from the patients next of kin. Patients fulfilling criteria for ALI/ARDS (8) were

eligible. Patients were not included in case of a leaking chest tube, contraindication to

sedation or paralysis, and respiratory or hemodynamic instability over the last 6 hours. Nine

patients were studied (Table 1).

Patients were sedated, paralyzed and mechanically ventilated in volume-controlled

mode. All had an 8.0-mm endotracheal tube. Tidal volume was 6-8 mlkg-1, respiratory rate

was 18-25 min-1, PEEP was chosen by the attending physician. The inspired oxygen

concentration was set to have pulse-oximeter oxygen saturation (SpO2) 92%.

Measurements

Changes in end-expiratory lung volume were measured by inductive plethysmography,

as previously described (9). The end-expiratory lung volume change was calculated as the

difference between the volumes measured at the end of expiration just before and at the end of

each suctioning procedure (Figure 1). Lung volume change was also measured following

suctioning, at the first breath after resuming baseline ventilation and after one minute, before

elastic pressure-volume (Pel-V) curves recording.

Pel-V curves from PEEP and from the static equilibrium volume at zero end-expiratory

pressure (ZEEP) were acquired before and one minute after each suctioning procedure, using

the low sinusoidal flow technique, as described (10, 11). Linear compliance at ZEEP and

PEEP-related alveolar recruitment/derecruitment at the elastic pressure of 20 cmH2O were

measured (10-15).

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SpO2 changes were calculated as the difference between the value before suctioning

and the minimum value recorded up to one minute after each suctioning procedure.

Signals were recorded and stored in a computer for subsequent analysis.

Details on measurement of end-expiratory lung volume, Pel-V curve, alveolar

recruitment, airway pressures and respiratory resistance are given in the online supplement.

Protocol (seedetails in online supplement)

A flow-chart of protocol and measurements is shown in Figure 2. Endotracheal

suctioning was performed:

1) after disconnection from the ventilator (DISCONNECTION);

2) without disconnection, introducing the suction catheter through the swivel adapter of the

catheter mount (SWIVEL);

3) with a closed suctioning system (CLOSED) (Hi-Care; Tyco Healthcare, CA, USA);

4) during SWIVEL, while triggering pressure-supported breaths at a peak inspiratory

pressure of 40 cmH2O during suctioning (SWIVELPSV );

5) during CLOSED, while triggering 40 cmH2O pressure-supported breaths during

suctioning (CLOSEDPSV) (Figure 1).

Trigger function was inhibited during procedures 1 to 3 and was set at 1 cmH2O during

phases 4 and 5. Suctioning techniques were performed in random order and were separated by

at least 30 min. The suction catheter (Fr 14) was inserted into the airways until resistance was

met and then pulled back 2 cm. Intermittent suctioning was started while the catheter was

gradually removed. Each suctioning maneuver lasted 25-30 seconds. Negative pressure was

set at 200 cmH2O.

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Statistics

Results are reported as meanSD. Comparison of suctioning techniques was made by

analysis of variance (Friedman test), and two-by-two comparisons were made using the

Wilcoxon test for paired samples. Regression analysis (Spearman rho) was used when

required.P

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RESULTS

End-expiratory lung volume

These data are shown in Figures 1 and 3, and Table 2. End-expiratory lung volume

decreased during endotracheal suctioning, whatever the technique. The largest end-expiratory

lung volume fall was observed with DISCONNECTION, and it was significantly different

from SWIVEL and CLOSED (-1466 586, -733 406 and -531 228 ml, respectively,

P

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curves recording, the end-expiratory lung volume was still not fully recovered with

DISCONNECTION, while it was almost totally restored with both SWIVEL and CLOSED

and increased with both SWIVELPSVand CLOSEDPSV(-278 239, -89 58, -44 53, 93

53 and 64 38 ml, respectively,P

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95.7 2.2, 96.2 2.7 and 96.1 2.2 % before DISCONNECTION, SWIVEL, CLOSED,

SWIVELPSV and CLOSEDPSV, respectively, P=NS). As shown in Figure 7, SpO2 decreased

with all the techniques used. However, the drop in SpO2was much greater when endotracheal

suctioning was performed after the disconnection from the ventilator than with all the other

techniques (-9.2 7.6, -1.7 0.9, -2.2 2.7, -1.5 0.6 and -1.3 0.6 % with

DISCONNECTION, SWIVEL, CLOSED, SWIVELPSV and CLOSEDPSV, respectively,

P

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endotracheal suctioning was performed while triggering pressure-supported breaths (P

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DISCUSSION

The main results of this study can be summarized as follows: 1) the drop in lung

volume observed during endotracheal suctioning resulted from both the loss of PEEP and the

application of a negative pressure; 2) avoiding disconnection during suctioning partially

avoided a large fall in lung volume, while performing a recruitment maneuver during

suctioning fully prevented a lung volume drop; 3) PEEP-induced recruitment decreased with

any suctioning techniques requiring the opening of ventilator circuit, but could be preserved

by using a closed system, and increased when performing a recruitment maneuver during

suctioning; 4) changes in arterial oxygen saturation paralleled changes in end-expiratory lung

volume, and oxygen saturation was virtually unaffected by endotracheal suctioning when the

drop in lung volume was avoided; 5) endotracheal suctioning-induced increase in airway

resistance was small and fully prevented by performing a recruitment maneuver during

suctioning.

Endotracheal suctioning-induced changes in end-expiratory lung volume

Endotracheal suctioning performed after disconnection from the ventilator may induce

a large lung volume drop and alveolar collapse, particularly in ALI/ARDS patients ventilated

with PEEP (4, 16). Indeed, endotracheal suctioning with disconnection induced almost 1.5 L

volume loss (Figures 1 and 3), similarly to the findings of Cereda et al. (4) in patients with

ALI/ARDS ventilated with comparable levels of PEEP (about 11 cmH2O, on average).

Brochard et al. in patients (3) and Lu et al. in sheep (5) found a smaller decrease in lung

volume when endotracheal suctioning was performed with disconnection from the ventilator

(about 400 ml), partly because low levels of PEEP (5 cmH2O) or no PEEP was used. The

large volume fall observed after disconnection, may suggest that PEEP could have produced

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some degree of alveolar overdistension (17). As well, disconnection may have allowed the

exhalation of gas, which was previously trapped in the lung as a result of dynamic

hyperinflation (18-20). The fall in lung volume during endotracheal suctioning after ventilator

circuit disconnection results both from the loss of the positive airway pressure generated by

mechanical ventilation with PEEP, and from the negative pressure applied during suctioning

(3, 5) (Figure 1). Interestingly, the lung volume fall due to the application of the negative

pressure alone, after disconnection, was identical to the drop in lung volume observed when

suctioning was performed without disconnection, suggesting that avoiding disconnection from

the ventilator allows to prevent approximately 50% of the lung volume fall observed during

suctioning after disconnection.

Performing endotracheal suctioning without disconnection from the ventilator,

through the swivel adapter of the catheter mount and with a closed system, limited the lung

volume fall but not to a full extent (Figures 1 and 3). This confirms that both the loss of the

positive airway pressure due to disconnection and the application of a negative pressure are

involved in the occurrence of the alveolar collapse associated with endotracheal suctioning.

This suggests that the use of a closed suctioning system could be recommended in patients

ventilated with high PEEP levels, who are at greater risk of large lung volume fall during

suctioning with conventional techniques.

The use of in-line suction catheters has been found effective in limiting or preventing

endotracheal suctioning-induced hypoxemia and lung volume fall (4, 21, 22). We observed a

decrease in end-expiratory lung volume with the closed-suction system, which was larger than

previously reported by Cereda et al. in similar patients (4). In the latter study, however, the

trigger sensitivity was set at 2 cmH2O and the ventilator was thus allowed to autocycle

during suctioning with the closed system, while this phenomenon did not occur in our study.

Ventilator autocycling during endotracheal suctioning could be efficient to compensate for

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some volume lost during suctioning and contribute to further prevent the lung volume drop

with the closed system, explaining the differences with the present study. This hypothesis is

confirmed by the fact that SpO2 did not change during suctioning with the closed-suction

system in the study by Cereda et al., while we found a small SpO2decrease (Figure 6). Our

results showed the pure effect of the closed system use on lung volume during endotracheal

suctioning, while the findings of Cereda et al. resulted by the combined effects of the closed-

suction system and specific ventilatory settings. In fact, the effect of a closed-suction system

on lung volume during suctioning may depend upon the ventilatory mode and settings, the

suctioning technique and duration, as well as the ratio between the diameters of the suction

catheter and the endotracheal tube (23-25).

Endotracheal suctioning-induced changes in alveolar recruitment

Changes in end-expiratory lung volume were measured together with true alveolar

recruitment. Although mathematically coupled, changes in end-expiratory lung volume and

recruitment are not equivalent (26). End-expiratory lung volume refers to PEEP-induced net

increase in lung volume above the elastic equilibrium volume of the respiratory system at

ZEEP. Alveolar recruitment is the amount of lung volume exceeding the volume increase

predicted by the pressure-volume relationship at ZEEP (27). Indeed, alveolar recruitment

expressed at 20 cmH2O, for instance, will vary with the amount of collapsed lung units which

can be reopened by the prolonged application of a continuous positive airway pressure. One

could imagine a situation where the lung volume loss is regained at the expense of a few

alveoli kept open and hyperinflated, while the more unstable alveoli cannot be reopened and

remain closed. Therefore, in patients with large lung areas remaining open and normally

aerated at ZEEP, endotracheal suctioning-induced changes in end-expiratory lung volume and

alveolar recruitment might be quite different.

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Several findings of the present study are consistent with the fact that the major

abnormality encountered with endotracheal suctioning is the fall in lung volume (Figure 5),

including the changes in compliance (3). These changes correlated with the changes in

alveolar recruitment and with the drop in SpO2. The larger the endotracheal suctioning-

induced fall in lung volume, the lower the short-term efficacy of PEEP to recruit collapsed

alveoli after suctioning, and the larger the decrease in SpO2. Indeed, the effect of PEEP on

alveolar recruitment is a time-dependent phenomenon and depends upon how much of the

lungs have been recruited during the previous ventilation, as recently reported (28).

Effect of endotracheal suctioning on oxygen saturation

We found that suctioning with the closed system and through the swivel adapter of the

catheter mount were equally effective in limiting the large oxygen desaturation observed

when endotracheal suctioning was performed disconnecting the patient from the ventilator

(Figure 6). Although SpO2 can sometimes poorly reflect the variations in arterial partial

pressure of oxygen (29), it is largely used in the clinical setting to monitor mechanically

ventilated patients (30). The correlations found between SpO2, alveolar recruitment and end-

expiratory lung volume, although weak, tend to reinforce a causal relationship. Other

mechanisms could explain the SpO2drop observed even when lung volume was maintained.

Suctioning could have induced hemodynamic changes, which, by modifying the

ventilation/perfusion ratio, could explain the transient impairment in SpO2 even when lung

volume was preserved. Another explanation could be that endotracheal suctioning-induced

bronchoconstriction may result in an increase in venous admixture (5). We observed only a

small increase in total respiratory system resistances after suctioning performed with

disconnection, through the swivel adapter and with the closed system, whereas it did not

change after the two techniques performed while triggering pressure-supported breaths. The

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small magnitude of these changes in the context of a decrease in lung volume makes difficult

to ascertain if this corresponded to a true bronchoconstriction or to the effects of lung volume

changes on respiratory system resistances. The increase in lung volume and alveolar

recruitment observed when a recruitment maneuver was performed during suctioning

counterbalanced the increase in total respiratory system resistances observed with the other

techniques.

Effect of endotracheal suctioning on the respiratory pressure-volume curve

Endotracheal suctioning-induced changes in alveolar recruitment were strongly

correlated with changes in linear compliance at ZEEP (Figure 7). In a recent study we found

that linear compliance above the lower inflection point may reflect the amount of lung areas

recruitable with PEEP (15). The tight relationship between suctioning-induced changes in

alveolar recruitment and in linear compliance we found in the present study supports this idea.

However, derecruitment caused by suctioning with ventilator disconnection was accompanied

by a decrease in linear compliance. We have previously shown that derecruitment induced by

decremental PEEP levels produced a progressive increase in linear compliance (15). In other

terms, the more recruitable the lung during the pressure-volume curve maneuver at ZEEP, the

higher the linear compliance. When PEEP is applied and the lung is recruited, there are less

recruitable lung areas and the linear compliance is lower. In the present study, the duration of

suctioning maneuvers and the amount of lung collapse could explain the lower linear

compliance observed after suctioning. In our previous study, the pressure-volume curve from

ZEEP was recorded after a single 6-sec expiration to the elastic equilibrium volume at ZEEP.

The lung areas, which collapsed during this expiration, were completely reopened during the

following large low-flow insufflation performed to record the pressure-volume curve. In this

context, a high linear compliance at ZEEP indicated that the collapsed lung areas were

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recruited during the large insufflation and could be kept open with PEEP. In the present study,

the duration of the suctioning procedure (30 seconds) and the large lung volume loss during

suctioning could make the collapsed lung areas much more difficult to recruit during

subsequent pressure-volume curve maneuver. Therefore, the lower compliance at ZEEP may

indicate that the lung zones collapsed during suctioning cannot be fully reopened during the

following pressure-volume curve. The lung volume fall during suctioning, below the

functional residual capacity, profoundly modified the pressure-volume relationship of the

respiratory system and may explain the bidirectional findings regarding linear compliance.

Prevention of endotracheal suctioning-related adverse events

It has been shown that repetitive alveolar collapse and reopening can be injurious for

the lung (6, 7, 31-33). Mead and coworkers showed, in a model of heterogeneous lung, that

atelectatic regions can be exposed to shear stress generated by the recruitment of collapsed

alveoli and the overdistension of the alveolar units adjacent to atelectatic zones (31). The

application of a negative pressure could further increase shear forces resulting in lung damage

(2). Lung injury resulting from repetitive alveolar opening and closing can affect the release

of inflammatory mediators into the lung and the systemic circulation (7, 33). Therefore,

preventing the periodic alveolar derecruitment induced by endotracheal suctioning could be

more clinically relevant than its reversal in patients with ALI/ARDS.

In the present study, using the triggering function of the ventilator during endotracheal

suctioning to deliver 40 cmH2O pressure-supported breaths seemingly induced a sort of

recruitment maneuver during suctioning. This maneuver fully prevented the suctioning-

induced derecruitment and can be incorporated in a global strategy to avoid derecruitment and

hypoxemia in the most severe ALI/ARDS patients (34). A previous study proposed the use of

a special, modified endotracheal tube as a method to prevent lung volume fall during

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suctioning (3). However, the clinical application of that method was greatly limited by the use

of special equipment. The present study describes a simplest way to fully prevent, not simply

reverse, endotracheal suctioning-related derecruitment.

Study limitations

The present study did not address the efficacy of the different suctioning techniques in

terms of quantity of secretions removed. However, the wall pressure, the catheter size, the

duration of suctioning and the technique for introducing and withdrawing the catheter, all

influencing the efficacy of endotracheal suctioning, were kept strictly similar during the

study. To our knowledge, no study has clearly shown a greater efficacy of a specific

suctioning procedure compared to others. Concern has been expressed about the efficacy of

the closed system in removing secretions. Few data exist on this issue, with anecdotal reports

suggesting a lower efficacy of the closed system compared to the conventional, open

technique (35). Nevertheless, in a study specifically addressing this issue, no significant

difference between the amount of secretions removed with the closed-circuit catheter and with

a conventional catheter was found (36). Increasing the degree of applied negative pressure can

increase the efficiency of suctioning, but also augments the risk for mucosal trauma (37).

Because patients were sedated and paralyzed, the effect of the studied suctioning

techniques in spontaneously breathing patients was not assessed. Avoiding paralysis might

partly prevent the lung volume fall during endotracheal suctioning, by allowing patients to

cough for instance. On the other hand, introducing the suction catheter into the airways

without interrupting mechanical ventilation may impede the ventilator to efficiently assist the

patient during suctioning, causing a major patient-ventilator dissynchrony and patient

discomfort (24). Therefore, the interference of the suction catheter with mechanical

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ventilation in spontaneously breathing patients, as well as the effect of specific ventilatory

modes and settings needs further studies.

In summary, we have found that, in ALI/ARDS patients, avoiding disconnection from

the ventilator and, more efficiently, using a closed-suction system allowed to minimize the

adverse effects of endotracheal suctioning on lung volume, alveolar recruitment and

oxygenation. A recruitment maneuver, performed by triggering pressure-supported breaths

during suctioning, fully prevented the lung volume fall and mechanical derangements of

respiratory system, allowing to increase alveolar recruitment.

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REFERENCES

1. International consensus conferences in intensive care medicine: Ventilator-associated lung

injury in ARDS.Am J Respir Crit Care Med1999;160:2118-2124.

2. Taskar V, John J, Evander E, Robertson B, Jonson B. Surfactant dysfunction makes lungs

vulnerable to repetitive collapse and reexpansion.Am J Respir Crit Care Med1997;155:313-

320.

3. Brochard L, Mion G, Isabey D, Bertrand C, Messadi AA, Mancebo J, Boussignac G, Vasile

N, Lemaire F, Harf A. Constant-flow insufflation prevents arterial oxygen desaturation during

endotracheal suctioning.Am Rev Respir Dis1991;144:395-400.

4. Cereda M, Villa F, Colombo E, Greco G, Nacoti M, Pesenti A. Closed system endotracheal

suctioning maintains lung volume during volume-controlled mechanical ventilation.Intensive

Care Med2001;27:648-654.

5. Lu Q, Capderou A, Cluzel P, Mourgeon E, Abdennour L, Law-Koune JD, Straus C,

Grenier P, Zelter M, Rouby JJ. A computed tomographic scan assessment of endotracheal

suctioning-induced bronchoconstriction in ventilated sheep. Am J Respir Crit Care Med

2000;162:1898-1904.

6. Amato MBP, Barbas CSV, Medeiros DM, Magaldi RB, Schettino GPP, Lorenzi-Filho G,

Kairalla RA, Deheinzelin D, Munoz C, Oliveira R, et al. Effect of a protective-ventilation

strategy on mortality in the acute respiratory distress syndrome. N Engl J Med1998;338:347-

354.

7. Ranieri VM, Suter PM, Tortorella C, De Tullio R, Dayer JM, Brienza A, Bruno F, Slutsky

AS. Effect of mechanical ventilation on inflammatory mediators in patients with acute

respiratory distress syndrome: a randomized controlled trial.JAMA1999;282:54-61.

7/25/2019 200203-195OCv1

21/54

R1

20

8. Bernard GR, Artigas A, Brigham KL, Carlet J, Falke K, Hudson L, Lamy L, Legall JR,

Morris A, Spragg R, et al. The American-European consensus conference on ARDS:

definitions, mechanisms, relevant outcomes, and clinical trial coordination.Am J Respir Crit

Care Med1994;149:818-824.

9. Dall'ava-Santucci J, Armaganidis A, Brunet F, Dhainaut JF, Chelucci GL, Monsallier JF,

Lockhart A. Causes of error of respiratory pressure-volume curves in paralyzed subjects. J

Appl Physiol1988;64:42-49.

10. Jonson B, Richard J-C, Straus C, Mancebo J, Lemaire F, Brochard L. Pressure-volume

curves and compliance in acute lung injury. Evidence of recruitment above the lower

inflection point.Am J Respir Crit Care Med1999;159:1172-1178.

11. Richard J-C, Maggiore SM, Jonson B, Mancebo J, Lemaire F, Brochard L. Influence of

tidal volume on alveolar recruitment. Respective role of PEEP and a recruitment maneuver.

Am J Respir Crit Care Med2001;163:1609-1613.

12. Ranieri VM, Eissa NT, Corbeil C, Chasse M, Braidy J, Matar N, Milic-Emili J. Effects of

positive end-expiratory pressure on alveolar recruitment and gas exchange in patients with the

adult respiratory distress syndrome.Am Rev Respir Dis1991;144:544-551.

13. Ranieri VM, Giuliani R, Fiore T, Dambrosio M, Milic-Emili J. Volume-pressure curve of

the respiratory system predicts effects of PEEP in ARDS: "Occlusion" versus "Constant flow"

technique.Am J Respir Crit Care Med1994;149:19-27.

14. Ranieri VM, Mascia L, Fiore T, Bruno F, Brienza A, Giuliani R. Cardiorespiratory effects

of positive end-expiratory pressure during progressive tidal volume reduction (permissive

hypercapnia) in patients with acute respiratory distress syndrome. Anesthesiology

1995;83:710-720.

15. Maggiore SM, Jonson B, Richard J-C, Jaber S, Lemaire F, Brochard L. Alveolar

derecruitment at decremental positive end-expiratory pressure levels in acute lung injury.

7/25/2019 200203-195OCv1

22/54

R1

21

Comparison with the lower inflection point, oxygenation, and compliance. Am J Respir Crit

Care Med2001;164:795-801.

16. De Campo T, Civetta JM. The effect of short-term discontinuation of high-level PEEP in

patients with acute respiratory failure. Crit Care Med1979;7:47-49.

17. Vieira SR, Puybasset L, Lu Q, Richecoeur J, Cluzel P, Coriat P, Rouby JJ. A scanographic

assessment of pulmonary morphology in acute lung injury. Significance of the lower

inflection point detected on the lung pressure-volume curve. Am J Respir Crit Care Med

1999;159:1612-1623.

18. Koutsoukou A, Armaganidis A, Stavrakaki-Kallergi C, Vassilakopoulos T, Lymberis A,

Roussos C, Milic-Emili J. Expiratory flow limitation and intrinsic positive end-expiratory

pressure at zero positive end-expiratory pressure in patients with adult respiratory distress

syndrome.Am J Respir Crit Care Med2000;161:1590-1596.

19. Koutsoukou A, Bekos B, Sotiropoulou C, Koulouris NG, Roussos C, Milic-Emili J.

Effects of positive end-expiratory pressure on gas exchange and expiratory flow limitation in

adult respiratory distress syndrome. Crit Care Med2002;30:1941-1949.

20. Vieillard-Baron A, Prin S, Schmitt JM, Augarde R, Page B, Beauchet A, Jardin F.

Pressure-volume curves in acute respiratory distress syndrome: clinical demonstration of the

influence of expiratory flow limitation on the initial slope. Am J Respir Crit Care Med

2002;165:1107-1112.

21. Carlon GC, Fox SJ, Ackerman NJ. Evaluation of a closed-tracheal suction system. Crit

Care Med1987;15:522-525.

22. Johnson KL, Kearney PA, Johnson SB, Niblett JB, MacMillan NL, McClain RE. Closed

versus open endotracheal suctioning: costs and physiologic consequences. Crit Care Med

1994;22:658-666.

7/25/2019 200203-195OCv1

23/54

R1

22

23. Baier H, Begin R, Sackner MA. Effect of airway diameter, suction catheters, and the

bronchofiberscope on airflow in endotracheal and tracheostomy tubes. Heart Lung

1976;5:235-8.

24. Craig KC, Benson MS, Pierson DJ. Prevention of arterial oxygen desaturation during

closed-airway endotracheal suction: effect of ventilator mode. Respir Care 1984;29:1013-

1018.

25. Taggart JA, Sheahan JS. Airway pressures during closed system suctioning. Heart Lung

1988;17:536-542.

26. Malbouisson LM, Muller JC, Constantin JM, Lu Q, Puybasset L, Rouby JJ. Computed

tomography assessment of positive end-expiratory pressure-induced alveolar recruitment in

patients with acute respiratory distress syndrome.Am J Respir Crit Care Med2001;163:1444-

1450.

27. Katz JA, Ozanne GM, Zinn SE, Fairley HB. Time course and mechanisms of lung-volume

increase with PEEP in acute pulmonary failure.Anesthesiology1981;54:9-16.

28. Crotti S, Mascheroni D, Caironi P, Pelosi P, Ronzoni G, Mondino M, Marini JJ, Gattinoni

L. Recruitment and derecruitment during acute respiratory failure . A clinical study. Am J

Respir Crit Care Med2001;164:131-140.

29. Van de Louw A, Cracco C, Cerf C, Harf A, Duvaldestin P, Lemaire F, Brochard L.

Accuracy of pulse oximetry in the intensive care unit. Intensive Care Med 2001;27:1606-

1613.

30. Jubran A. Pulse oximetry. In: Tobin MJ, editor. Principles and practice of intensive care

monitoring. New York: McGraw Hill; 1998, p. 261-288.

31. Mead J, Takishima T, Leith D. Stress distribution in lungs: a model of pulmonary

elasticity.J Appl Physiol1970;596-608.

7/25/2019 200203-195OCv1

24/54

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23

32. Muscedere JG, Mullen JBM, Gari K, Bryan AC, Slutsky AS. Tidal ventilation at low

airway pressures can augment lung injury.Am J Respir Crit Care Med1994;149:1327-1334.

33. Chiumello D, Pristine G, Slutsky AS. Mechanical ventilation affects local and systemic

cytokines in an animal model of acute respiratory distress syndrome. Am J Respir Crit Care

Med1999;160:109-116.

34. NIH ARDS Trials Network. Prospective, randomized, multi-center trial of higher end-

expiratory lung volume/lower FiO2 versus lower end-expiratory lung volume/higher FiO2

ventilation in acute lung injury and acute respiratory distress syndrome. Assessment of low

tidal volume and elevated end-expiratory volume to obviate lung injury (ALVEOLI). Study

protocol available at http://hedwig.mgh.harvard.edu/ardsnet/.

35. Noll ML, Hix CD, Scott G. Closed tracheal suction systems: effectiveness and nursing

implications.AACN Clin Issues Crit Care Nurs1990;1:318-328.

36. Witmer MT, Hess D, Simmons M. An evaluation of the effectiveness of secretion removal

with the Ballard closed-circuit suction catheter.Respir Care1991;36:844-848.

37. Kuzenski BM. Effect of negative pressure on tracheobronchial trauma. Nurs Res

1978;27:260-263.
http://hedwig.mgh.harvard.edu/ardsnet/http://hedwig.mgh.harvard.edu/ardsnet/http://hedwig.mgh.harvard.edu/ardsnet/

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FIGURE LEGENDS

Figure 1

Tracings of airway pressure and volume, measured by thoracic respiratory inductive

plethysmography, during endotracheal suctioning procedures in a representative patient (#3).

Changes in end-expiratory lung volume (EELV tot) were measured as the difference

between the value of end-expiratory lung volume of the cycle immediately preceding the

suctioning procedure and the minimum value recorded during suctioning. When suctioning

was performed after disconnecting patient from the ventilator, a first drop in lung volume was

observed after disconnection (DISCONNECTION) followed by a second drop (NEGATIVE

PRESSURE) when negative pressure was applied. In this patient, disconnection from the

ventilator contributed more than negative pressure to the total lung volume fall recorded

during the entire suctioning procedure. Positive end-expiratory pressure was totally lost

during DISCONNECTION, partially maintained during SWIVEL and CLOSED, and fully

preserved when pressure-supported breaths were triggered during suctioning. Note the

pressure drop at the beginning of the suctioning maneuver with SWIVEL, related to the

opening of the swivel adapter of the catheter mount before introducing the suction catheter.

This pressure drop was avoided with the closed system. When suctioning was performed after

switching from volume-control to pressure support ventilation, trigger sensitivity was set at

1 cmH2O and pressure support was set in order to have a peak inspiratory pressure of 40

cmH2O. In such a way, as suctioning was performed intermittently, pressure-supported

breaths were triggered only when the negative pressure was applied.

DISCONNECTION: endotracheal suctioning performed after the disconnection from the

ventilator; SWIVEL: endotracheal suctioning performed through the swivel adapter of the

catheter mount; CLOSED: endotracheal suctioning performed with the closed system;

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SWIVELPSV: endotracheal suctioning performed through the swivel adapter of the catheter

mount, while triggering pressure-supported breaths during suctioning; CLOSEDPSV:

endotracheal suctioning performed with the closed system, while triggering pressure-

supported breaths during suctioning.

Figure 2

Flow-chart of the protocol and measurements with the studied suctioning techniques. Elastic

pressure-volume curves from positive end-expiratory pressure and from zero end-expiratory

pressure were acquired five minutes before endotracheal suctioning and forty-five seconds to

one minute after suctioning. End-expiratory lung volume was measured just before

suctioning, at the end of endotracheal suctioning, one breath after suctioning and forty-five

seconds to one minute after suctioning, just before pressure-volume curves recording. Arterial

oxygen saturation was continuously recorded before, during and after endotracheal suctioning

up to pressure-volume curves recording. Each suctioning procedure (insertion of the suction

catheter, intermittent suctioning and catheter removal) lasted 25 to 30-s.

PEEP: positive end-expiratory pressure; ZEEP: zero end-expiratory pressure; Pel-V curves:

elastic pressure-volume curves; SpO2: pulse oximeter oxygen saturation; EELV: end-

expiratory lung volume.

Figure 3

Changes in end-expiratory lung volume during endotracheal suctioning, one breath and one

minute after suctioning with the studied techniques. A very large drop in end-expiratory lung

volume was observed with DISCONNECTION. The fall in lung volume was limited with

SWIVEL and CLOSED (P

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was performed during suctioning (P

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suctioning through the swivel adapter, while triggering pressure-supported breaths during

suctioning; E = endotracheal suctioning with a closed system, while triggering pressure-

supported breaths during suctioning.

Figure 5

Values of PEEP-induced alveolar recruitment measured before (open bars) and after (black

bars) endotracheal suctioning with the studied techniques. After suctioning, recruitment was

significantly smaller with DISCONNECTION and SWIVEL. It did not change with

CLOSED, while it increased significantly with both SWIVELPSVand CLOSEDPSV.

Vrecr: alveolar recruitment; DISCONNECTION: endotracheal suctioning performed after the

disconnection from the ventilator; SWIVEL: endotracheal suctioning performed through the

swivel adapter of the catheter mount; CLOSED: endotracheal suctioning performed with the

closed system; SWIVELPSV: endotracheal suctioning performed through the swivel adapter of

the catheter mount, while triggering 40 cmH2O pressure-supported breaths during suctioning;

CLOSEDPSV: endotracheal suctioning performed with the closed system, while triggering 40

cmH2O pressure-supported breaths during suctioning.

*P

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Figure 7

Individual and mean values of the drop in arterial oxygen saturation observed during

endotracheal suctioning with the studied techniques. Data were not available for patient #2.

The changes in arterial oxygen saturation with SWIVEL, CLOSED, SWIVELPSV and

CLOSEDPSVwere significantly smaller than with DISCONNECTION.

SpO2: changes in pulse oximeter oxygen saturation; DISCONNECTION: endotracheal

suctioning performed after the disconnection from the ventilator; SWIVEL: endotracheal

suctioning performed through the swivel adapter of the catheter mount; CLOSED:

endotracheal suctioning performed with the closed system; SWIVELPSV: endotracheal

suctioning performed through the swivel adapter of the catheter mount, while triggering 40

cmH2O pressure-supported breaths during suctioning; CLOSEDPSV: endotracheal suctioning

performed with the closed system, while triggering 40 cmH2O pressure-supported breaths

during suctioning.

Figure 8

Correlation between changes in linear compliance of the elastic pressure-volume curve

recorded from zero end-expiratory pressure and in alveolar recruitment with the studied

suctioning techniques.

CLIN at ZEEP: changes in linear compliance of the pressure-volume curve from zero end-

expiratory pressure; Vrecr: changes in alveolar recruitment.

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TABLE 1

General characteristics of the patients.

Patient

No.

Age

(y)

Cause of

ALI/ARDS

Underlying

disease

PaO2/FiO2

(mmHg)

PEEPEXT

(cmH2O)

PEEPi

(cmH2O) FiO2 LIS

Days of

mechanical

ventilation

Days of

ALI/ARDS Outcome

1 32

Acute

pancreatitis

Nephrotic

syndrome93 10 2.1 1 3.25 22 2 Died

2 77

Alveolar

hemorrhage

Aortic stenosis 180 10 4.5 1 2.5 3 3 Survived

3 57 Pneumonia Diabetes 75 13 2.6 1 3 1 1 Survived

4 76 Pneumonia Aortic stenosis 226 12 2.5 0.5 2.5 8 8 Survived

5 38

Subarachnoid

hemorrhageViral hepatitis 190 10 1.9 0.5 2.75 1 1 Survived

6 55

Massive blood

transfusion

Aortic aneurysm 176 16 3.1 0.5 3 2 2 Survived

7 35 Sepsis

Acute lymphoid

leukemia100 14 1.8 0.6 3.5 11 8 Died

8 46 Pneumonia Alcoholism 92 12 4.6 1 3.5 4 4 Died

9 57 Pneumonia Renal cancer 157 12 3.4 0.7 2.75 3 3 Survived

Mean 53 143 12 3 0.75 2.97 6 4

SD 17 54 2 1 0.24 0.38 7 3

Definition of abbreviations: ALI: acute lung injury; ARDS: acute respiratory distress

syndrome; PEEPEXT: external positive end-expiratory pressure; PEEPi: intrinsic positive end-

expiratory pressure; LIS: lung injury score.

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TABLE 2

Individual values of change in end-expiratory lung volume during and just after endotracheal

suctioning, with the studied suctioning technique.

# EELV during suctioning (ml) EELV just after suctioning (one breath) (ml)

DISCONNECTION SWIVEL CLOSED SWIVELPSV CLOSEDPSV DISCONNECTION SWIVEL CLOSED SWIVELPSVCLOSEDPSV

1 -1416 -666 -502 -213 -213 -1114 -115 -96 42 -154

2 -884 -276 -222 -106 -46 -578 -40 -80 142 100

3 -1962 -1155 -833 -115 -157 -1280 -95 -169 4 31

4 -1452 -839 -705 -471 -841 -1067 -260 73 -301 2

5 -571 -466 -295 15 -141 -556 -230 -83 153 -76

6 -1846 -1195 -553 -442 -789 -1325 -491 -299 -79 -130

7 -843 -394 -693 -112 -9 -671 -168 -190 -11 19

8 -2092 -1307 -253 -26 -31 -1921 -1017 -102 51 65

9 -2124 -301 -726 -47 -325 -1530 -70 -155 65 -5

Mean -1466 -733 * -531 * -168 * -284 * ll -1116 -276 * -122 * 7 * -16 *

SD 586 406 228 176 317 460 310 101 136 86

Definitions of abbreviations: EELV: change in end-expiratory lung volume;



catheter mount; CLOSED: endotracheal suctioning with the closed system; SWIVELPSV:

endotracheal suctioning performed through the swivel adapter of the catheter mount, while

triggering pressure-supported breaths during suctioning; CLOSEDPSV: endotracheal

suctioning performed with the closed system, while triggering pressure-supported breaths

during suctioning.

* P

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TABLE 3

Changes in pressure-volume curve from zero end-expiratory pressure and respiratory

mechanics with the different endotracheal suctioning techniques.

DISCONNECTION SWIVEL CLOSED SWIVELPSV CLOSEDPSV

Before After Before After Before After Before After Before After

PLIP, cmH2O 13.5 3 12.5 2.4 12.9 3.3 13.1 3.2 14.6 2.8 14.1 1.7 13.1 3.1 16 2.7 * 14.1 3.6 16 3

VLIP, ml 241 171 152 83 208 126 201 131 280 202 209 146 196 111 356 210 * 257 173 297 173

C1, ml/cmH2O 28.1 15.9 21 7.1 * 25.7 11.2 26.6 11.3 28.9 18.1 23.8 15.8 24.9 8.8 36.3 23.8 * 26.7 14.2 28.6 16

CLIN, ml/cmH2O 71.1 23.1 65.5 20.7 70.6 19.1 65.9 18.1 68.3 19.3 68 19.6 67.9 20.8 75.5 22.7 67.6 20.4 72.8 22

PPEAK, cmH2O 32.8 3.8 34 4.5 32.9 4 34.2 5.4 32.8 3.7 32.3 3.2 33 3.7 31 3.4 32.7 3.8 30.7 3.8

PPLAT, cmH2O 26.6 4 26.9 3.6 26.7 3.9 26.6 4.8 26.7 3.6 25.9 3 * 26.8 4 25.2 3.8 * 27 3.9 25.1 3.9

RRS, cmH2OL-1s-1 10.2 1.4 11.9 3.5 * 10.3 1.6 12.6 3 * 9.8 2.2 10.5 2.3 10.3 1.2 9.6 2.1 9.2 2 9.2 2.1

Definitions of abbreviations: PLIP: pressure at the lower inflection point of the pressure-

volume curve from zero end-expiratory pressure; VLIP: volume at the lower inflection point of

the pressure-volume curve from zero end-expiratory pressure; C1: compliance of the first part

of the pressure-volume curve from zero end-expiratory pressure, below the lower inflection

point; CLIN: compliance of the linear segment of the pressure-volume curve from zero end-

expiratory pressure, above the lower inflection point; PPEAK: peak airway pressure; PPLAT:

end-inspiratory plateau pressure; RRS: total respiratory resistance; DISCONNECTION:

endotracheal suctioning performed after the disconnection from the ventilator; SWIVEL:

endotracheal suctioning performed through the swivel adapter of the catheter mount;

CLOSED: endotracheal suctioning performed with the closed system; SWIVELPSV:




during suctioning.

*P

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Figure 1

EELV totDISCONNECTION

NEGATIVE

PRESSURE

0

10

20

30

40

50

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

ES

Airway

Pressure

(cm

H2

O)

Vo

lume

(ml)

0

10

20

30

40

50

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

EELV tot

ES

Airway

Pressure

(cm

H2

O)

Vo

lume

(ml)

0

10

20

30

40

50

-2500

-2000

-1500

-1000

0

500

1000

1500

ES

EELV tot-500

Airway

Pressure

(cm

H2

O)

Vo

lume

(ml)

*

0

10

20

30

40

50

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

ES

*EELV tot

Airway

Pressure

(cm

H2

O)

V

olume

(ml)

0

10

20

30

40

50

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

ES

*EELV tot

*

Airway

Pressure

(cm

H2

O)

Vo

lume

(ml)

DISCONNECTION SWIVEL

CLOSED SWIVELPSV

CLOSEDPSV

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Figure 2

PEEP and ZEEP

Pel-V curves

PEEP and ZEEP

Pel-V curves

SpO2EELV

curves

SpO2EELV

1 breath aftersuctioning

SpO2EELV

Just beforesuctioning

SpO2EELV

End of suctioning

Just beforePel-V

5-min 45-s to1-minSuctioning

(25 to 30-s)

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Figure 3

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

200

EELV(ml)

p < 0.001 p < 0.001

After suctioning

(one breath)SuctioningBefore suctioning

p < 0.001

After suctioning

(45-s to 1-min)

DISCONNECTION

SWIVEL

CLOSED

CLOSEDPSV

SWIVELPSV

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Figure 4

A

B

C

D

E

0

350

700

1050

1400

0 10 20 30 40 50

0

350

700

1050

1400

0 10 20 30 40 50

Volume(ml)

0

350

700

1050

1400

0 10 20 30 40 50

0

350

700

1050

1400

0 10 20 30 40 50

Volume(ml)

0

350

700

1050

1400

0 10 20 30 40 50

0

350

700

1050

1400

0 10 20 30 40 50

V

olume(ml)

Volume(ml)

0

350

700

1050

1400

0 10 20 30 40 50

0

350

700

1050

1400

0 10 20 30 40 50

0

350

700

1050

1400

0 10 20 30 40 50

0

350

700

1050

1400

0 10 20 30 40 50

Volume(ml)

Elastic Pressure (cm H2O)

Before suctioning After suctioning

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Figure 5

0

100

200

300

400

500


Vre

cr(ml)

Before suctioning

After suctioning

* *

* *

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Figure 6

-200

-150

-100

-50

0

50

100

150

200

-900 -450 0 450 900

EELV 1-min after suctioning (ml)

Vrecr(ml)

DISCONNECTION

SWIVEL

CLOSED

CLOSEDPSV

SWIVELPSV

Y = 6.9 + 0.28 X,

rho = 0.88, p < 0.001

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Figure 7

-25

-20

-15

-10

-5

0

DISCONNECTION SWIVEL CLOSED

SpO

2

(%)

Pt #1

Pt #3

Pt #4

Pt #5

Pt #6

Pt #7

Pt #8

Pt #9

mean

SWIVELPSV CLOSEDPSV

p < 0.05 p < 0.05 p < 0.05 p < 0.05

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Figure 8

-30

-20

-10

0

10

20

30

-150 -100 -50 0 50 100 150

Vrecr (%)

C

LIN

atZEEP(%)

Y = 1.1 + 0.2 X,

rho = 0.9, p < 0.001

DISCONNECTION

SWIVEL

CLOSED

CLOSEDPSV

SWIVELPSV

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ONLINE-DATA SUPPLEMENT

Prevention of Endotracheal Suctioning-induced Alveolar Derecruitment in Acute Lung

Injury

Salvatore M. MAGGIORE1, Franois LELLOUCHE2, Jrme PIGEOT2, Solenne TAILLE2,

Nicolas DEYE2, Xavier DURRMEYER2, Jean-Christophe RICHARD3, Jordi MANCEBO4,

Franois LEMAIRE2, Laurent BROCHARD2

1 Department of Anesthesiology and Intensive Care, Agostino Gemelli Teaching Hospital,

Universit Cattolica del Sacro Cuore, Rome, Italy; 2Medical Intensive Care Unit, INSERM

U492, Henri Mondor Teaching Hospital, AP-HP, Paris XII University, Crteil, France; 3

Medical Intensive Care Unit, Charles Nicolle Teaching Hospital, Rouen, France; 4Servei de

Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain

Send all correspondence including reprint requests to:

Prof. L. Brochard, Ranimation Mdicale, Hpital Henri Mondor, 94000 Crteil, France.

Phone: +33 1 49 81 23 92; Fax: +33 1 42 07 99 43;

E-mail: [email protected]

This study was supported by INSERM U492. The equipment was kindly furnished by TYCO

Healthcare, CA, USA.

Running Title: Endotracheal Suctioning in Acute Lung Injury

Descriptor numbers:2 - 10 -13

Word count (text without references): 1625
mailto:[email protected]:[email protected]

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METHODS

Measurement of end-expiratory lung volume

Changes in end-expiratory lung volume (EELV) were measured by respiratory

inductive plethysmography (RIP) (AMI Model 150; Ambulatory Monitoring Inc., NY, USA)

operating in the DC mode. This is a differential linear transformer, composed of a sensor

mounted on a flexible but non-extensible belt and positioned around the patient at the nipple

level, as previously described (E1-E3). Because in the DC-coupled mode the oscillator drift is

sensitive to temperature (E4), we waited for 60 minutes before taking any measurements to

allow for thermal equilibrium. In paralyzed subjects, the respiratory system can be considered

a system with a single degree of freedom, without variation of thoraco-abdominal partitioning

of volume (E1). Therefore, since all patients were paralyzed, changes in lung volume were

computed from a single signal, the rib cage displacement. To verify the validity of this

assumption, the double-coil, thoracic and abdominal, RIP was used in five paralyzed patients.

The RIP deflections for the thoracic and the abdominal coils were highly correlated (R2

0.97) with and directly proportional to the volume measured by integrating the signal obtained

from a heated calibrated Fleisch No. 1 pneumotachygraph (Lausanne, Switzerland), connected

to a differential pressure transducer (Validyne MP45 2.5 cmH2O; Northridge, CA, USA)

and inserted between the endotracheal tube and the ventilator circuit. Signals were digitized at

200 Hz and sampled using an analogic/digital system (MP100; Biopac systems, Santa

Barbara, CA). The calibration procedure was conducted during mechanical ventilation by

comparing EELV measured by thoracic RIP with the integrated flow signal obtained from

the pneumotachygraph. Calibration lines were calculated by linear regression and all

coefficients of linear regression (R2) were 0.96. Mean Y-intercept was 0.02 0.14 mV and

not different from zero (P=NS). EELV was calculated as the difference between the volume

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measured at the end of expiration just before suctioning and the volume measured at the end

of suctioning. EELV was also measured at the end of expiration of the first breath following

endotracheal suctioning, back in volume-controlled mode, and one minute after suctioning,

before elastic pressure-volume (Pel-V) curves recording. Because the drift of the RIP signal

could affect measurement of lung volume, we recorded in each patient the signal of the RIP

thoracic coil over 5 minutes before each suctioning maneuver, without interfering with the

basal ventilation and after calibrating the instrument. This time interval was considered

sufficient for the drift assessment because the signal recording performed to assess lung

volume changes during and after suctioning lasted approximately 90 seconds (30 seconds

during suctioning and 60 seconds after suctioning). The 5-min baseline drift of RIP averaged

0.5 6.9 ml and changed over a narrow range in single patients (min -8.5 8.3 ml, max 13.4

22.5 ml) and between the different suctioning techniques (min -5.4 10.6 ml, max 6.1

23.1 ml) (P=NS).

When suctioning was performed after disconnection from the ventilator, the

contribution of disconnection from the ventilator alone and of negative pressure to the total

lung volume drop was quantified. Looking at the RIP tracings recorded during suctioning

performed after disconnection, it was possible to identify a first drop in lung volume

immediately after disconnection, followed by a second drop when the negative pressure was

applied. The first drop was the EELV due to disconnection alone, while the second drop was

the additional EELV induced by applying the negative pressure. Their sum was the EELV

due to the whole suctioning procedure.

Measurement and analysis of elastic pressurevolume curves

The system including a computer controlled Servo Ventilator 900C (Siemens-Elema

AB, Solna, Sweden) and the technique for acquiring Pel-V curves, based on the low flow

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insufflation method, have been previously described in detail (E5-E7). Volumes were

measured as BTPS. The signals were fed into the computer and A/D converted at 50 Hz.

Application of analog signals to the external control socket of the ventilator permitted the

computer to control ventilatory rate, level of positive end-expiratory pressure (PEEP), and

minute volume. The external control signal had an immediate effect. If the external signal for

minute ventilation was oscillating during a specific inspiration, this led to a modulated

oscillating inspiratory flow. This allowed Pel-V curves to be obtained either from PEEP or

from zero end-expiratory pressure (ZEEP). After an expiration prolonged to 8 s, during which

the pressure was either maintained at PEEP or decreased to ZEEP, a high volume was

insufflated during a 6-s-long inspiratory phase. This volume was set in order to maintain end-

inspiratory pressure below 50 cmH2O. If the pressure reached 50 cmH2O before the volume

was entirely delivered, the insufflation was automatically stopped. During insufflation, the

flow was sinusoidally modulated at 1 Hz. This variation in flow rate made it possible to

calculate inspiratory resistances of the respiratory system for further subtraction from the

pressure signal, thus allowing the elastic pressure of the respiratory system to be computed.

The following expiration was prolonged in order to allow complete expiration of the high

insufflated volume.

The recorded data for flow and pressure from the insufflation period were analyzed in

order to construct the Pel-V curve. The data were transferred to a spreadsheet (EXCEL 7.0

Microsoft), where the analysis was automatically performed. The different steps required to

determine the elastic pressure from the measured total airway pressure have been recently

described (E5-E7). Total resistive pressure gradient from the Y-piece was calculated from

tube and respiratory system resistances, and Pelwas obtained by subtracting resistive pressure

from measured airway pressure.

Each Pel-V curve was mathematically analyzed using a sigmoid model (E5, E8) that

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divides each curve into three segments separated by the lower inflection point (LIP) and the

upper inflection point (UIP). The segment before the LIP and the segment after the UIP are

curvilinear and have low compliance values. The steeper segment between LIP and UIP has

higher compliance (CLIN), and is considered linear. LIP and UIP are defined as the points

where the statistical analysis indicates that the Pel-V curve begins to deviate from a straight

line. Accordingly, LIP corresponds to the point where the second derivative of the equation

used for the Pel-V curve mathematical fitting reaches its maximum value. Similarly, UIP

corresponds to the minimum value of the second derivative of the equation.

Pelas a function of volume is described as follows.

Below the LIP:

(1.1) Pel= PLIP- (VLIP- VMIN)/CLIN ln [(VMIN- VLIP)/(VMIN V)]

Between LIP and UIP:

(1.2) Pel= PLIP+ (V VLIP)/CLIN

Above the UIP:

(1.3) Pel= PUIP+ (VMAX VUIP)/CLIN ln [(VMAX VUIP)/(VMAX V)]

VLIP and PLIP are volume and pressure at LIP, respectively, and VUIP and PUIP are

volume and pressure at UIP, respectively. Below LIP, compliance increases linearly with the

inflated volume from zero (minimal lung volume, VMIN) to VLIP. At the linear segment

between LIP and UIP, the relationship is described by the coefficients VLIPand CLIN. Above

UIP, compliance falls linearly with additional volume, from CLIN to zero at maximum

distension of the lungs, i.e., at VMAX. The coefficients that define the Pel-V curve (i.e., VMIN,

VLIP, CLIN, VUIP, VMAX) are estimated from raw data using a numerical technique involving

determination of the least sum of squared deviations between measured Peland the equation

describing Pelas a function of volume.

The effective compliance of the first segment of the Pel-V curve recorded from ZEEP

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(C1), below LIP, was calculated as: C1 = VLIP/ PLIP intrinsic PEEP.

Measurement of alveolar recruitment

PEEP and ZEEP Pel-V curves were plotted on the same volume axis, using PEEP-

related end-expiratory lung-volume change measured during the passive expiration from

PEEP to ZEEP. PEEP-related alveolar recruitment was defined, for a given elastic pressure,

by the volume difference between both curves (E5-E7, E9-E11). This volume represented the

PEEP-induced recruitment of previously collapsed lung units, and was identified by the

upward shift of the PEEP Pel-V curve, relative to the ZEEP Pel-V curve. Alveolar recruitment

was measured at the elastic pressure of 20 cmH2O (E5-E7, E9-E11) (Figure 1).

Measurement of airway pressures and total respiratory resistance

Airway pressure was measured with a differential pressure transducer (MP45,

Validyne, Northridge, CA) connected to the distal end of the endotracheal tube. Peak

inspiratory pressure (PPEAK) and airway pressure 3-5 seconds after the onset of an end-

inspiratory occlusion (PPLAT) were measured just before and after each suctioning procedure.

Values of airway pressure at end-expiration of a regular breath (PEEPEXT) and 35 seconds

after the onset of an end-expiratory occlusion (PEEPTOT) were measured at the beginning of

the protocol. Intrinsic (PEEPi) was computed as the difference between PEEPTOT and

PEEPEXT. Total respiratory resistance (RRS) was calculated as Rtot = (Ppeak - Pplat)/.

V ,

where.

Vis the inspiratory flow.

Protocol

A 30-min washout period of baseline ventilation was allowed between each suctioning

procedure. For each studied technique, the baseline end-expiratory lung volume was the value

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of end-expiratory lung volume of the cycle immediately preceding the suctioning procedures.

When the suctioning maneuver was performed without disconnection from the

ventilator (passing the suction catheter through the swivel adapter of the catheter mount and

using the closed system), while switching to pressure support ventilation, the trigger

sensitivity was set at 1 cmH2O in order to trigger the ventilator while applying the negative

pressure. Therefore, as suctioning was performed intermittently, the fall in airway pressure

triggered pressure-supported breaths only when the negative pressure was applied. In the 30-

sec duration of the entire suctioning procedure (opening the endotracheal tube, insertion of the

suction catheter, intermittent suctioning, removal of the suction catheter, and closing the

endotracheal tube) an average of 9 pressure-supported breaths were delivered (9.44 1.67 and

9 2.06 breaths with suctioning through the swivel adapter while triggering pressure-

supported breaths and with the closed system while triggering pressure-supported breaths,

respectively).

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REFERENCES

E1. Dall'ava-Santucci J, Armaganidis A, Brunet F, Dhainaut JF, Chelucci GL, Monsallier JF,

Lockhart A. Causes of error of respiratory pressure-volume curves in paralyzed subjects. J

Appl Physiol1988;64:42-49.

E2. Brochard L, Mion G, Isabey D, Bertrand C, Messadi AA, Mancebo J, Boussignac G,

Vasile N, Lemaire F, Harf A. Constant-flow insufflation prevents arterial oxygen desaturation

during endotracheal suctioning.Am Rev Respir Dis1991;144:395-400.

E3. Cereda M, Villa F, Colombo E, Greco G, Nacoti M, Pesenti A. Closed system

endotracheal suctioning maintains lung volume during volume-controlled mechanical

ventilation.Intensive Care Med2001;27:648-654.

E4. Hudgel DW, Capehart M, Johnson B, Hill P, Robertson D. Accuracy of tidal volume,

lung volume, and flow measurements by inductance vest in COPD patients. J Appl Physiol

1984;56:1659-1665.

E5. Jonson B, Richard J-C, Straus C, Mancebo J, Lemaire F, Brochard L. Pressure-volume

curves and compliance in acute lung injury. Evidence of recruitment above the lower

inflection point.Am J Respir Crit Care Med1999;159:1172-1178.

E6. Richard J-C, Maggiore SM, Jonson B, Mancebo J, Lemaire F, Brochard L. Influence of

tidal volume on alveolar recruitment. Respective role of PEEP and a recruitment maneuver.

Am J Respir Crit Care Med2001;163:1609-1613.

E7. Maggiore SM, Jonson B, Richard J-C, Jaber S, Lemaire F, Brochard L. Alveolar

derecruitment at decremental positive end-expiratory pressure levels in acute lung injury.

Comparison with the lower inflection point, oxygenation, and compliance. Am J Respir Crit

Care Med2001;164:795-801.

E8. Svantesson C, Drefeldt B, Sigurdsson S, Larsson A, Brochard L, Jonson B. A single

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computer-controlled mechanical insufflation allows determination of the pressure-volume

relationship of the respiratory system.J Clin Monit Comput1999;15:9-16.

E9. Ranieri VM, Eissa NT, Corbeil C, Chasse M, Braidy J, Matar N, Milic-Emili J. Effects of

positive end-expiratory pressure on alveolar recruitment and gas exchange in patients with the

adult respiratory distress syndrome.Am Rev Respir Dis1991;144:544-551.

E10. Ranieri VM, Giuliani R, Fiore T, Dambrosio M, Milic-Emili J. Volume-pressure curve

of the respiratory system predicts effects of PEEP in ARDS: "Occlusion" versus "Constant

flow" technique.Am J Respir Crit Care Med1994;149:19-27.

E11. Ranieri VM, Mascia L, Fiore T, Bruno F, Brienza A, Giuliani R. Cardiorespiratory

effects of positive end-expiratory pressure during progressive tidal volume reduction

(permissive hypercapnia) in patients with acute respiratory distress syndrome.Anesthesiology

1995;83:710-720.

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FIGURE LEGEND

Figure E1

Mean changes in linear compliance of the elastic pressure-volume curve recorded from the

static equilibrium volume at zero end-expiratory pressure with the studied suctioning

techniques. Linear compliance decreased with both DISCONNECTION and SWIVEL

(P

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TABLE E1

Individual values of pressure at the lower inflection point of the elastic pressure-volume curve

recorded from zero end-expiratory pressure, before and after endotracheal suctioning, with the

studied techniques.

# PLIPbefore suctioning (cmH2O) PLIPafter suctioning (cmH2O)

DISCONNECTION SWIVEL CLOSED SWIVELPSV CLOSEDPSV DISCONNECTION SWIVEL CLOSED SWIVELPSVCLOSEDPSV

1 14.6 15.6 13.1 14.0 14.0 13.3 14.6 12.6 15.6 15.2

2 14.9 15.9 15.6 17.5 16.0 15.6 17.5 14.6 16.4 16.6

3 11.5 8.3 13.3 8.7 11.2 7.8 8.0 12.1 15.3 13.3

4 14.4 13.2 17.3 13.8 14.5 13.0 13.0 14.0 16.0 19.8

5 17.1 16.8 18.6 15.2 16.0 12.0 15.7 13.4 19.4 17.9

6 16.7 15.4 15.4 15.0 13.6 14.7 14.8 16.0 17.5 17.4

7 10.1 12.1 16.3 13.5 21.0 12.9 9.8 17.2 17.6 18.7

8 13.9 11.3 12.4 12.9 12.4 10.6 11.0 13.0 17.0 14.6

9 7.9 7.9 9.5 7.6 7.9 6.9 7.2 8.3 9.6 10.1

Mean 13.5 12.9 14.6 13.1 14.1 12.5 13.1 14.1 16.0* 16.0

SD 3.0 3.3 2.8 3.1 3.6 2.4 3.2 1.7 2.7 3.0

Definitions of abbreviations: PLIP: pressure at the lower inflection point of the pressure-

volume curve from zero end-expiratory pressure; DISCONNECTION: endotracheal



endotracheal suctioning with the closed system; SWIVELPSV: endotracheal suctioning

performed through the swivel adapter of the catheter mount, while triggering pressure-

supported breaths during suctioning; CLOSEDPSV: endotracheal suctioning performed with

the closed system, while triggering pressure-supported breaths during suctioning.

*P

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TABLE E2

Individual values of volume at the lower inflection point of the elastic pressure-volume curve

recorded from zero end-expiratory pressure, before and after endotracheal suctioning, with the

studied techniques.

# VLIPbefore suctioning (ml) VLIPafter suctioning (ml)

DISCONNECTION SWIVEL CLOSED SWIVELPSV CLOSEDPSV DISCONNECTION SWIVEL CLOSED SWIVELPSV CLOSEDPSV

1 139 192 154 93 160 123 191 120 179 195

2 108 120 144 168 144 112 94 98 150 100

3 458 206 622 229 470 176 235 531 658 513

4 190 130 303 170 208 145 178 167 226 332

5 584 532 612 461 549 315 529 343 696 619

6 291 200 163 152 116 107 137 169 256 209

7 130 200 228 246 420 250 148 249 376 326

8 106 158 63 136 98 85 193 71 480 131

9 162 130 231 107 148 58 103 135 184 247

Mean 241 208 280 196 257 152 201 209 356* 297

SD 171 126 202 111 173 83 131 146 210 173

Definitions of abbreviations: VLIP: volume at the lower inflection point of the pressure-

volume curve from zero end-expiratory pressure; DISCONNECTION: endotracheal



endotracheal suctioning with the closed system; SWIVELPSV: endotracheal suctioning

performed through the swivel adapter of the catheter mount, while triggering pressure-

supported breaths during suctioning; CLOSEDPSV: endotracheal suctioning performed with

the closed system, while triggering pressure-supported breaths during suctioning.

*P

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TABLE E3

Individual values of compliance of the first segment of the elastic pressure-volume curve

recorded from zero end-expiratory pressure, below the lower inflection point, before and after

endotracheal suctioning, with the studied techniques.

# C1 before suctioning (ml/cmH2O) C1 after suctioning (ml/cmH2O)

DISCONNECTION SWIVEL CLOSED SWIVELPSV CLOSEDPSV DISCONNECTION SWIVEL CLOSED SWIVELPSV CLOSEDPSV

1 13.2 15.2 14.0 13.2 13.3 12.1 17.5 15.2 15.5 14.8

2 18.3 16.4 23.6 22.7 20.9 17.8 15.2 15.3 20.3 13.4

3 61.0 39.6 68.3 40.2 59.4 33.9 40.5 63.2 63.9 63.3

4 15.3 11.6 22.1 15.3 18.4 14.7 17.8 14.2 17.9 23.2

5 38.2 35.2 37.3 32.9 37.4 29.7 38.1 28.8 40.5 39.2

6 33.9 26.0 19.6 20.8 18.7 16.3 20.1 21.1 27.2 24.9

7 13.4 17.7 14.9 19.9 23.3 21.9 15.6 16.2 22.8 19.3

8 23.0 41.6 15.4 31.7 19.3 19.7 39.4 13.6 85.8 20.4

9 36.8 27.8 44.5 27.5 29.5 23.2 35.5 27.0 32.9 38.7

Mean 28.1 25.7 28.9 24.9 26.7 21.0* 26.6 23.8 36.3* 28.6

SD 15.9 11.2 18.1 8.8 14.2 7.1 11.3 15.8 23.8 16.0

Definitions of abbreviations: C1 = compliance of the first segment of the pressure-volume

curve recorded from zero end-expiratory pressure, below the lower inflection point;



catheter mount; CLOSED: endotracheal suctioning with the closed system; SWIVELPSV:




during suctioning.

*P

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Figure E1

-20

-15

-10

-5

0

5

10

15

20


CLIN

atZEEP(%)

*

*

*

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